See https://travis-ci.org/wikimedia/pywikibot/jobs/314284813
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ERROR: test_url_image (tests.proofreadpage_tests.TestProofreadPageValidSite)
Test fetching of url image of the scan of ProofreadPage.
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Traceback (most recent call last):
File "/home/travis/build/magul/pywikibot-core/tests/proofreadpage_tests.py", line 293, in test_url_image
self.assertEqual(page.url_image, self.valid_redlink['url_image'])
File "/home/travis/build/magul/pywikibot-core/pywikibot/proofreadpage.py", line 537, in url_image
self._url_image = self._url_image.find('img')
AttributeError: 'NoneType' object has no attribute 'find'